| First Author | Shoeb F | Year | 2003 |
| Journal | J Biol Chem | Volume | 278 |
| Issue | 4 | Pages | 2503-14 |
| PubMed ID | 12427763 | Mgi Jnum | J:81725 |
| Mgi Id | MGI:2449877 | Doi | 10.1074/jbc.M208525200 |
| Citation | Shoeb F, et al. (2003) Cloning and Functional Characterization of the Smooth Muscle Ether-a-go-go-related Gene K+ Channel. POTENTIAL ROLE OF A CONSERVED AMINO ACID SUBSTITUTION IN THE S4 REGION. J Biol Chem 278(4):2503-14 |
| abstractText | The human ether-a-go-go-related gene (HERG) product forms the pore-forming subunit of the delayed rectifier K(+) channel in the heart. Unlike the cardiac isoform, the erg K(+) channels in native smooth muscle demonstrate gating properties consistent with a role in maintaining resting potential. We have cloned the smooth muscle isoform of HERG, denoted as erg1-sm, from human and rabbit colon. erg1-sm is truncated by 101 amino acids in the C terminus due to a single nucleotide deletion in the 14th exon. Sequence alignment against HERG showed a substitution of alanine for valine in the S4 domain. When expressed in Xenopus oocytes, erg1-sm currents had much faster activation and deactivation kinetics compared with HERG. Step depolarization positive to -20 mV consistently produced a transient outward component. The threshold for activation of erg1-sm was -60 mV and steady-state conductance was approximately 10-fold greater than HERG near the resting potential of smooth muscle. Site-directed mutagenesis of alanine to valine in the S4 region of erg1-sm converted many of the properties to that of the cardiac HERG, including shifts in the voltage dependence of activation and slowing of deactivation. These studies define the functional role of a novel isoform of the ether-a-go-go-related gene K(+) channel in smooth muscle. |
